Pot and Mental Illness


A reader writes:

I'm afraid your reader is only getting half the story with his thesis that marijuana use is solely self-medication for people with mental illness. In the comments section of the Guardian two days ago, there were similar sentiments, as well as some more extreme versions of "pot is never bad".  This all reminds me in some ways of the false debate over the "autism epidemic" and its fictitious causation by either Thimerisol (America) or simply the MMR jab (Britain). The idea is "it won't happen to me, so I'm gonna smoke to my heart's content". Yes, mentally ill people self-medicate with cannabis. They might well receive symptomatic relief, but only at the cost of doing further severe damage to their neural pathways. It's like giving a diabetic with low blood sugar a Twinkie.

I am diagnosed with bipolar disorder. My baseline mood level is depressed, except when life conspires through anxiety to ramp me into hypomania. I began to experience depressive cycles when I was fifteen years old,  which became more and more pronounced throughout my undergraduate and graduate education.  Finally I suffered a mental breakdown causing me to leave law school a day before my first-year exams.

I was also a frequent -- at times daily -- user of marijuana between my 18th and 24th years. Though I didn't know it at the time, I was indeed self-medicating. THC has certain GABAergic properties that mimic the anti-convulsants used for treating bipolar disorder.  The difference is that anti-convulsants both shield neural deterioration and encourage neural restoration. Marijuana only increases the neurotoxicity of mental illness.

Dopamine withdrawal creates some very odd and paradoxical effects. Most everyone has experienced the eventual dip in energy after drinking several cups of coffee or soda.  This is caused by what is called dopamine downregulation.  Put very, very simply -- and I admit to not being fully up on the science here, being trained in philosophy instead --, the brain changes its structure through time.  It gets very used, very quickly, to having increased amounts of dopamine, but it doesn't know what to do when it is no longer there.  Because of the receptor's need for increased dopamine, any decrease in availability of the neurotransmitter causes withdrawal effects.  I would assume that psychoses, schizophrenia and mood disorders can be caused by changes to neural circuitry, in this case the dopaminergic.  But plasticity in certain areas of the brain only goes so far.  Eventually the brain loses its ability to go heal itself.  In bipolarity this is called the "kindling theory".  It is the primary explanation for the development of the disorder.  It also explains why not everyone genetically predisposed to mental illness develops it.  It takes both genetic and behavioural causes to cause the symptoms.  In the case of drug use, however, you are instilling an artificial causation.  Schizophrenia, in particular, has been linked to dopaminergic dysfunction.

It is a shame that this particular study, which is only a literature review, was the one publicized in such sensational terms. There are much better direct studies out there that a simple PubMed search would reveal.  I am fully aware that you have better things to do than to sort through a large number of abstracts, so I apologise in advance for bombarding you with so many links.  I only do so to prove a quantitative point. 

Many people will claim that to prove the link between schizophrenia and cannabis use there need be a corresponding increase in cases of schizophrenia over the last thirty years or so, which does not exist.  Yet there is growing proof to the contrary.  A recent Swiss study found that not only did admissions and diagnoses of Schizophrenia increase during the 90s, but that the numbers coincided almost exactly with the increase in cannabis use amongst adolescents and young adults during that period:


See also:


Furthermore, there are ample studies on the effects of cannabis use in psychotic, schizophrenic, bipolar and depressed patients -- the exception being anxiety disorders, though cannabis abuse can cause some sort of odd obsessive behaviour where the user is compelled to constantly bathe in very hot water.  The conclusion is almost universally the same.  Cannabis use increases greatly the chance of increased symptoms for those with preexisting conditions, but also, to a somewhat lesser extent, in those without, even when controlled for demographic and situational data, including the possibility of self-medication.  Furthermore, the incidence of schizophrenia in cannabis users is significantly higher than non-users.  For instance:


There are literally dozens more studies suggesting the same damn thing.

Lastly, it cannot be concluded that the cost to society isn't great.  Far greater than the suggested 800 additional cases in Britain.  Mental health issues are an enormous burden on economies, resulting in lost work hours, an increased strain on public health systems and a major cost to public pensions and social welfare systems.  If mental illness results from cannabanoid use, the increased burden directly corresponds to the increase in diagnoses, with the additional cost of treating the comorbid substance abuse disorder. 


On a more human level cost analysis, cannabis use increases the risk of suicide correspondingly in persons with mental illnesses:


I am a libertarian: I do not believe cannabis should be illegal. The costs to society are probably no more than that associated with alcohol or tobacco use. Furthermore, cannabis has legitimate medical uses. It is not risk free, however. People really need to be aware of that fact, particularly those with a predisposition to mental illness.  Unfortunately, I learned the hard way.